Cichoń Karolina, Bak-Sypien Irena I, Basko Malgorzata, Kost Bartłomiej
Centre of Molecular and Macromolecular Studies Polish Academy of Sciences Sienkiewicza 112, 90-363 Lodz, Poland.
Macromolecules. 2023 Aug 16;56(17):6951-6967. doi: 10.1021/acs.macromol.3c01343. eCollection 2023 Sep 12.
New functionalized lactide copolymers containing acetal units were prepared for the first time in a controlled manner that enabled the regulation of the number of reactive groups introduced into the polyester chain. The presence of functional groups in the copolymer backbone provided chemical modification sites, and the nature of the acetal unit affected the material degradability. First, paraformaldehyde was reacted with selected diols containing reactive pendant groups (3-allyloxypropane-1,2-diol and 3-chloropropane-1,2-diol), which was catalyzed by -toluenesulfonic acid, to synthesize new cyclic acetals with different functionalities (allyl- or chloro-). In addition, using butane-1,4-diol, a nonfunctionalized seven-membered cyclic acetal (dioxepane) was obtained for comparative studies. In the next step, the prepared cyclic acetals were used for cationic copolymerization with lactide in the presence of glycol as an initiator and triflic acid as a catalyst. Different temperatures (-15, 2, and 30 °C) and copolymerization times (24, 48, 72, and 192 h) were investigated to produce copolyesters with variable contents of acetal units in the range of 5-27%. The copolymers' structure and molar masses were carefully investigated using H, C NMR, 2D NMR, and size-exclusion chromatography. Moreover, the ability of functionalized copolymers to perform post modifications was also proven by the reaction with sodium azide and propanethiol. Finally, we speculate that structurally diverse groups can be attached to the copolyester chain, fine-tuning the on-demand properties, which could rapidly expand the library of polylactide-based materials.
首次以可控方式制备了含有缩醛单元的新型功能化丙交酯共聚物，这种方式能够调节引入聚酯链中的反应性基团数量。共聚物主链中官能团的存在提供了化学修饰位点，并且缩醛单元的性质影响材料的降解性。首先，多聚甲醛与含有反应性侧基的选定二醇（3-烯丙氧基丙烷-1,2-二醇和3-氯丙烷-1,2-二醇）反应，在对甲苯磺酸催化下，合成具有不同官能度（烯丙基或氯）的新型环状缩醛。此外，使用1,4-丁二醇获得了用于比较研究的非功能化七元环状缩醛（二氧杂环庚烷）。在下一步中，将制备的环状缩醛在二醇作为引发剂和三氟甲磺酸作为催化剂的存在下与丙交酯进行阳离子共聚。研究了不同温度（-15、2和30℃）和共聚时间（24、48、72和192小时），以制备缩醛单元含量在5 - 27%范围内可变的共聚酯。使用氢谱、碳谱、二维核磁共振谱和尺寸排阻色谱对共聚物的结构和摩尔质量进行了仔细研究。此外，功能化共聚物进行后修饰的能力也通过与叠氮化钠和丙硫醇的反应得到了证实。最后，我们推测结构多样的基团可以连接到共聚酯链上，按需微调性能，这可能会迅速扩展聚丙交酯基材料的库。
